Why we use FSL-1.1-MIT (and why our sister MCPs are MIT)

A practical write-up of our two-license strategy, the FSL gives commercial protection on the hosted API; plain MIT keeps the 9 sister packages enterprise-friendly.

We ship ten public packages and one hosted API. We use two different licenses:

The 9 free public MCP servers (abs-mcp, rba-mcp, ato-mcp, apra-mcp, aihw-mcp, asic-mcp, aemo-mcp, au-weather-mcp, wgea-mcp) → MIT
The hosted REST API (ausdata-api) → FSL-1.1-MIT

This post explains why, and what it means for you as a customer or contributor.

What's FSL-1.1-MIT?

The Functional Source License (FSL) is a 2023 license created by Sentry. It's a delayed-open-source license:

For two years after publication, you can use the code for any non-competing purpose, internal use, learning, modifications, contributions
After two years, the license auto-converts to plain MIT, no friction, no negotiation, fully OSI-compatible

The non-compete clause is narrow:

> "Permitted Purpose means any purpose other than a Competing Use."

> "Competing Use means making the Software available to others in a commercial product or service that competes with the Software."

In plain English: you can read it, modify it, run it internally, fork it, contribute. You can't take ausdata-api, rebrand it, and resell it as a competing hosted API. Anyone else can do anything else.

Why we don't use plain MIT on the hosted API

If ausdata-api were MIT, anyone could take the entire code base, including the cross-source signals, the cache layer, the auth model, and run it as a competing hosted service on day 1. The cost of building everything else (UI, auth, billing, marketing, customer support) is non-trivial, and we're a one-person company.

FSL gives us a 2-year window to build the product before strict MIT applies. After 2 years (May 2028), the protection lapses and the code is fully MIT, exactly like Apache 2.0 + a delayed-open-source patent grant.

The companies using FSL-1.1 right now: Sentry, GitButler, Convex, Keygen, our peers in dev-tools.

Why the sister MCPs stay MIT

The 9 sister MCPs (abs-mcp etc.) are infrastructure for the entire AU data ecosystem. We want:

Enterprise legal teams to never have an excuse to ban them
Academic / public-sector users to use them in research without license review
Other library authors to import them as dependencies without polluting their license tree
Future maintainers (us or anyone else) to be able to fork them if we disappear

MIT is the lowest-friction, most-recognised permissive license. CC-BY (which the upstream agencies use for the data) and MIT (for our code wrapping the data) compose cleanly.

If we used FSL on the sisters, every academic paper using abs-mcp would need to read a 4-paragraph license clause. Every enterprise procurement team would need to ask their lawyer about "Competing Use." That friction kills adoption. The sisters' job is to be free funnel infrastructure.

The bundle (private, commercial) and the hosted API (FSL-1.1-MIT, commercial) are where we put the moat. The sisters are how everyone else benefits.

Practical implications

You can:

pip install any of the 9 sister MCPs and use them in any product, free
npm install ausdata-mcp and use it client-side, free
Read the ausdata-api source on GitHub and run it locally for development, free
Modify ausdata-api for internal use at your company, free
Fork ausdata-api for personal experimentation, free
Contribute back to any of these repos via PR, free

You can't:

Take ausdata-api, brand it as your own API, and resell it as a competing hosted service (until May 2028)

You don't have to:

Get a commercial license for any normal use case, the FSL covers "any purpose other than competing"
Ask permission for anything you'd otherwise do under MIT

The 2028 date

May 16, 2028, two years from initial publication of ausdata-api. On that date, the license auto-converts to plain MIT and the protection ends. By then we hope to have either:

A profitable business that doesn't need legal moats, or
A clear failure case where we walk away and the code is fully open

Both outcomes are fine.

What this means for your purchase decision

If you're evaluating ausdata.io for production use:

Read the LICENSE file directly, it's <200 words
We're happy to talk to enterprise legal teams about specific concerns
The 9 sister MCPs you'd otherwise vendor stay MIT, you can always self-host on top of those instead of paying us, if FSL doesn't fit your procurement model

No tricks. Honest two-license strategy. The hosted product gets light commercial protection; the underlying infrastructure stays as open as possible.